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Octopuses Can Edit Their Own Genes, So the Revolution Is Probably Coming

April 24, 2017

Written byAshley Hamer

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You may not know what coleoid cephalopods are, but you've definitely seen them in viral videos. They include octopuses, which can open jars from the inside; squids, which can communicate by changing color; and cuttlefish, whose camouflage skills are unparalleled. They're the smartest invertebrates on Earth, and scientists may have just figured out why: They can actually edit their own genes.

Thanks, Evolution — They'll Take It From Here

In 2017, researchers reported in the journal Cell that octopuses, squids, and cuttlefish don't follow their DNA's commands like the rest of us mortals. Instead, they do what's known as RNA editing. Here's how it works: Usually, RNA acts as a sort of messenger and copyist for DNA — DNA hands over genetic information to the RNA, which it uses to help create particular proteins in cells. But in these animals, that information can be changed in translation. Enzymes can swap out certain nucleotides in the RNA's code — you may know them as the letters A, U, G, and C — for others, thereby creating proteins that were never encoded in the DNA. As The New York Times puts it, this can allow an organism to "add new riffs to its base genetic blueprint."

Scientists already knew this was happening — it even happens every so often with our own RNA — but the 2017 study was designed to figure out just how much these animals were using the technique. The answer? A lot. Consider this: Humans have 20,000 genes but only a few dozen places where RNA editing takes place. Squids also have 20,000 genes but have at least 11,000 active RNA editing sites. As Tel Aviv University biophysicist and study co-author Eli Eisenberg said in a press release, "With these cephalopods, this is not the exception. This is the rule. The rule is that most of the proteins are being edited." Most of those edits happen in the animals' nervous system, which suggests that it may contribute to their wicked smarts. Previous research pointed to the possibility that they used RNA editing to quickly adapt to changes in temperature.

Good News and Bad News

All good things come with a trade-off. The researchers also found that where RNA editing was happening, DNA mutation wasn't. Since DNA mutation is the main way organisms adapt and evolve to better survive and procreate, this reliance on RNA editing slows down the evolution of coleoid cephalopods considerably. "We know there's a price," says Eisenberg. "The price is slowing down genome evolution ... Cephalopods probably chose to take this RNA bargain over genome evolution, and maybe vertebrates made the other choice — they preferred genome evolution over editing." To each their own, we suppose.

Want to learn how scientists are editing DNA in humans? Listen to our conversation with Dr. Sam Sternberg, CRISPR expert and protein-RNA biochemist, on the Curiosity Podcast. Stream or download the episode using the player below, or find it everywhere podcasts are found, including iTunes, Stitcher, and Gretta.